The research activities anticipated for the coming year are designed to further our understanding of the role of the cyclic AMP dependent protein kinase and of its substrate. We intend to continue our efforts to isolate and phosphorylate the components of the various subcellular membranes (e.g., plasma membranes, mitochondrial membranes), and to relate phosphorylation with changes in calcium transport. In addition we are planning to continue our study of the phosphoprotein phosphatase (both soluble and microsomal). We hope to be able to find conditions that inhibit microsomal phosphoprotein phosphatase activity without affecting microsomal calcium transport. BIBLIOGRAPHIC REFERENCES: Sands, H., Sinclair, D. and Mascali, J. Cyclic AMP and Protein Kinase in the Spontaneously Hypertensive Rat Aorta and Tissue Cultured Aortic Smooth Muscle Cells. Blood Vessels 13:361-373, 1976. Sands, H., Penberthy, W., Meyer, T.A., and Jorgensen, R., Cyclic AMP-Stimulated Phosphorylation of Bovine Tracheal Smooth Muscle Contractile and Non-contractile Proteins. Biochem. Biophys. Acta 447: 791-801, 1976.